Failed to import extension

I have a message "Failed to import extension - please check the log file" when I try to install a new version of Vizlib (Whatever version I tried - also I am in premium enterprise version).

I got the log, there's this message in the QlikSense System_Repository.txt :

"Failed to add extension  Duplicate extension (the extension already exists or occurs more than once in the ZIP file): VizlibActivityGauge "

Anybody experienced that (I have already opened a ticket) ?